Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method of processing an emergency call in a wireless communication system, and an apparatus supporting the method.
Related Art
3GPP (3rd Generation Partnership Project) LTE (long term evolution) which is improvement of UMTS (Universal Mobile Telecommunications System) has been introduced as 3GPP release 8. The 3GPP LTE uses OFDMA (orthogonal frequency division multiple access) in a downlink, and uses SC-FDMA (Single Carrier-frequency division multiple access) in an uplink. The 3GPP LTE adopts MIMO (multiple input multiple output) having maximum four antennas. Recently, a discussion of 3GPP LTE-A (LTE-Advanced) which is the evolution of the 3GPP LTE is in progress.
A user equipment (UE) which is a representative mobile device may experience a radio link failure (RLF) with respect to a network providing a wireless communication service. At the occurrence of the RLF, the UE performs a cell selection procedure for a radio resource control (RRC) connection re-establishment procedure. In the cell selection procedure, if the UE fails to select a suitable E-UTRA cell (hereinafter, a suitable cell) or a cell using another radio access technique (RAT) within a specific time, the UE transitions to an RRC-idle state.
Meanwhile, an emergency call is supported in a communication standard such as LTE/LTE-A or the like. In the conventional technique, however, if the UE performs an emergency call in an acceptable cell in which only a limited service can be received and if the RLF occurs in this process, since the UE transitions to the RRC-idle state when the UE fails to select the suitable cell or the cell using another RAT within the specific time, there is a problem in that the emergency call ends. There is a need for a method and apparatus for solving this problem.